A conventional swash plate type compressor, which is widely used as a compressor of an air conditioner for an automobile, includes a disk-shaped swash plate having a certain inclination and fixedly installed at a drive shaft for transmitting thee power of an engine by being rotated by the drive shaft, and a plurality of pistons installed around the outer perimeter of the swash plate by interposing shoes between the swash plate and the pistons. By rotation of the swash plate, the pistons are reciprocated in a straight line in a plurality of cylinder bores formed in a cylinder block, thereby sucking, compressing, and discharging refrigerant gas.
Recently, a variable displacement swash plate type compressor has been proposed to provide a more comfortable feeling in an automobile. In the compressor, the inclination of the swash plate is varied according to thermal load to control an amount of refrigerant gas conveyed by the pistons to thereby accomplish precise temperature control, and at the same time, the inclination is continuously changed to attenuate rapid variation in engine torque due to the compressor.
FIG. 1 illustrates a conventional variable displacement swash plate type compressor disclosed in Japanese Patent Laid-open Publication No. 1999-336657, the contents of which will be described hereinafter.
The conventional variable displacement swash plate type compressor includes a cylinder block 2 having a plurality of cylinder bores formed in parallel in a longitudinal direction of an inner peripheral surface thereof, a front housing 1 hermetically sealed in front of the cylinder block 2, and a rear housing 3 hermetically sealed behind the cylinder block 2 by interposing a valve plate 8 therebetween.
A swash plate chamber 26 is formed in the front housing 1, and a drive shaft 4 is disposed through the swash plate chamber 26. For this purpose, one end of the drive shaft 4 is rotatably supported by disposing a bearing 11 at the center of the front housing 1, and the other end of the drive shaft 4 is supported by bearings 12 and 14 in a center hole of the cylinder block 2.
In addition, a swash plate 5 having an inclination angle that varies while moving along a plate section 32 is installed at the drive shaft 4, and a spring 18 is interposed between the center hole of the cylinder block 2 and the swash plate 5 to resiliently support the swash plate 5.
Two plates are installed in parallel with a centerline of the drive shaft 4 at the front surface of the swash plate 5 when the swash plate 5 is disposed perpendicular to the drive shaft 4, and each plate has a circular hole. In addition, a pin 31 is inserted into the circular hole.
In addition, the plate section 32 has a guide surface 33 linearly inclined to the swash plate 5 on its outer surface. When the compressor operates, since the swash plate 5 is inclined, the pin 31 moves along the guide surface 33.
Further, since the plate section 32 is interposed between the plates, the swash plate 5 rotates together with the drive shaft 4.
When the swash plate 5 rotates in an inclined state, the pistons 6 inserted into the periphery surface of the swash plate 5 are reciprocated, through the shoes 7, in the cylinder bores of the cylinder block 2.
In addition, a suction chamber 23 and a discharge chamber 22 are formed at the rear housing 3, and a suction hole 25 and a discharge hole 24 are formed corresponding to the cylinder bores at the valve plate 8 interposed between the rear housing 3 and the cylinder block 2.
A suction lead and a discharge lead are formed at the suction hole 25 and the discharge hole 24 formed at the valve plate 8 to open and close the suction hole 25 and the discharge hole 24 using pressure variation due to the reciprocation of the pistons 6.
As shown in FIG. 1, in the conventional variable displacement swash plate type compressor, the inclination angle of the swash plate 5 is adjusted corresponding to a difference between the pressure in the swash plate chamber 26 and the suction pressure in the cylinder bores so that a stroke of the piston 6 connected to the swash plate 5 varies depending on the inclination angle of the swash plate 5 to vary a discharge capacity of the compressor.